The present invention relates generally to an electromagnetic relay, and more particularly to a compact electromagnetic relay that is mounted on a circuit board.
In the prior art, Japanese Patent Application Kokoku No. H4-42766 describes a conventional electromagnetic relay, which is shown in FIG. 7.
The electromagnetic relay comprises an insulating base housing 110, a contact part 120, an operating electromagnet 130 and a case 140.
The base housing 110 is formed with wall members 115 and 116 protruding on both ends of a substantially rectangular body that extends in a longitudinal direction, and includes insertion holes 111 and 112 formed in the front sides of the respective wall members 115 and 116 (toward the front in FIG. 5). Insertion parts 131a (only one insertion part 131a is shown in FIG. 5) on a gate-form iron core 131 are each press-fitted into a respective one of the insertion holes 111,112. A circular receiving hole 113 is formed in close proximity to a corner of the insertion hole 111 on the side of the wall member 115 and receives a leg 133d of an armature 133. In addition, a receiving groove 114 is formed in close proximity to a corner of the insertion hole 112 on the side of the wall member 116 and receives a protrusion 133f of the armature 133 and regulates the pivoting range of the armature 133. A pair of through-holes 117 are formed in the wall member 116 and allow the passage of coil terminals 135.
The contact part 120 comprises a fixed contact 121 and a movable contact 123. The fixed contact 121 and movable contact 123 have a fixed contact point 122 and a movable contact point 124, respectively, on facing surfaces, and have board connecting portions (not shown) that are connected to a circuit board (not shown). The fixed contact 121 and movable contact 123 are formed by stamping and forming copper alloy plates consisting of phosphorus bronze, etc. The fixed contact 121 and movable contact 123 are fastened to the wall member 115 of the base housing 110 so that they are arranged beneath the excitation coil 134 and between the two legs 131b of the gate-form iron core 131.
The operating electromagnet 130 comprises a gate-form iron core 131, a winding frame 132 fastened to the gate-form iron core 131 by press-fitting, an armature 133, and an excitation coil 134.
The gate-form iron core 131 is formed in the shape of a gate-form flat plate with a body (not shown) extending in the horizontal direction and a pair of legs 131b (only one leg 131b is shown) extending downward from both ends of the body. The core 131 is formed by stamping an iron core. Insertion parts 131a, press-fitted in the insertion holes 111 and 112, protrude from the lower ends of the legs 131b of the gate-form iron core 131. A projection 131c is formed on an upper portion of one end of the gate-form iron core 131.
The winding frame 132 comprises a winding body (not shown) with a U-shaped cross section which extends in the horizontal direction and which has a U-shaped groove open at the top, flanges 132a arranged on both ends of the winding body, and a terminal 132b which extends to one side as a continuation of one of the flanges 132a. The winding frame 132 is formed by molding an insulating synthetic resin. The body of the gate-form iron core 131 is press-fitted in the U-shaped groove of the winding body of the winding frame 132, so that the gate-form iron core 131 and the winding frame 132 are formed into an integral unit. Two coil terminals 135 are fastened to the terminal 132b. The excitation coil 134 is wound around the circumference of the winding body of the winding frame 132, and the ends of the excitation coil 134 are connected to a respective one of the coil terminals 135.
The armature 133 is constructed with an inverted gate shape by stamping an iron plate, and comprises a horizontal portion 133a extending in the horizontal direction, and a pair of vertical portions 133b and 133c extending upward from both ends of the horizontal portion 133a. A leg 133d acts as a support for the armature 133 and protrudes from a lower end of the vertical portion 133b on one end of the armature 133. A protrusion 133f, used to regulate the pivoting range of the armature 133, protrude from the lower end of the vertical portion 133c on the other end of the armature 133. A recess 133e, mated with the projection 131c of the gate-form core 131, is formed in the upper end of the vertical portion 133b on one end of the armature 133 on the axial line of the leg 133d. An insulating operating part 133g is mounted on the horizontal portion 133a of the armature 133.
The operating electromagnet 130, constructed as described above, is installed on the base housing 110 by press-fitting both insertion parts 131a of the gate-form iron core 131 in the insertion holes 111 and 112, inserting the leg 133d of the armature 133 into the receiving hole 113 of the base housing 110, and inserting the protrusion 133f into the receiving groove 114. At the same time, the coil terminals 135 are passed through the through-holes 117 in the base housing 110. In this manner, the leg 133d is supported in the receiving hole 113, and the recess 133e on the axial line of the leg 133d engages with the projection 131c. In view of this assembly, the armature 133 can pivot about the leg 133d and the recess 133e on the axial line of the leg 133d. The armature 133 receives a spring force via the operating part 133g from the movable contact 123, which also acts as a return spring, so that in the non-excited state of the excitation coil 134, the vertical portion 133c on the second end of the armature 133 is separated from the gate-form iron core 131. On the other hand, when the excitation coil 134 is excited, the vertical portion 133c on the second end of the armature 133 pivots about the leg 133d and the recess 133e located on the axial line of the leg 133d, and is caused to adhere to the gate-form iron core 131. As a result, the movable contact 123 is pressed so that it undergoes elastic deformation, thus causing the contact points 122 and 124 to close.
The case 140 is a substantially rectangular member with an accommodating space (not shown) formed inside that covers the base housing 110 and the operating electromagnet 130 installed on the base housing 110. The case 140 covers the base housing 110 and operating electromagnet 130, and is anchored to the base housing 110. A projection (not shown) is arranged in the accommodating space of the case 140 to press against the upper end on the side of the projection 131c of the gate-form iron core 131 and another projection (not shown) is arranged in the accommodating space to prevent the upper end of the vertical portion 133b on the pivoting fulcrum side (first end) of the armature 133 from tilting when the base housing 110 and operating electromagnet 130 are covered.
The electromagnetic relay constructed as described above provides an ultra-compact magnetic relay inexpensively and with high productivity.
Another conventional electromagnetic relay is shown in FIG. 8 and is described more fully in Japanese Patent No. 3011334. The electromagnetic relay has an operating electromagnet comprising a gate-form iron core 231 which has a body 231a extending in a horizontal direction and first and second legs 231b and 231c each extending from a respective end of the body 231a, an insulating winding frame 232 which is attached to the body 231a and around the circumference of which an excitation coil 234 is wound, and an armature 233. The armature 233 has a horizontal portion 233a which extends in the horizontal direction and on which an insulating operating part 235 is arranged, a pivoting shaft 233b which extends from one end of the horizontal portion 233a in the direction of extension of the first leg 231b, and a vertical portion 233c which extends from the other end of the horizontal portion 233a, and which contacts the second leg 231c when the excitation coil 234 is excited. The operating electromagnet is received inside an insulating base housing 210. When the armature 233 is received in the base housing 210, the armature 233 is guided by a guide wall 211 protruding from the base housing 210. A movable contact 221 and a fixed contact 222 are fastened to the base housing 210 so that they are arranged on one side of the excitation coil 234 (on the front side in FIG. 8) between the first and second legs 231b and 231c of the gate-form iron core 231.
The armature 233 receives a spring force via a protrusion 235a of the operating part 235 from the movable contact 221, which also acts as a return spring, so that the vertical portion 233c located on the side of the second end of the armature 233 is separated from the gate-form iron core 231 when the excitation coil 234 is in a non-excited state. On the other hand, when the excitation coil 234 is excited, the vertical portion 233c located on the side of the second end of the armature 233 pivots about the pivoting shaft 233b and adheres to the gate-form iron core 231. As a result, the movable contact 221 is pressed so that it undergoes elastic deformation, thus causing a contact point of the movable contact part 221 and a contact point of the fixed contact 222 to close.
The base housing 210 and the operating electromagnet arranged on the base housing 210 are covered by a case 240.
Reference numeral 236 in FIG. 8 designates a hinge spring which is used to press the pivoting shaft 233b of the armature 233 against the gate-form iron core 231.
However, the following problems have been encountered in these conventional electromagnetic relays.
In the electromagnetic relay shown in FIG. 7 (that of Japanese Patent Application Kokoku No. H4-42766), only the operating part (insulating part) 133g fastened to the armature 133 is present between the excitation coil 134 and armature 133 on the one hand, and the movable and fixed contacts 123 and 121 on the other hand. Accordingly, the insulating distance between the primary side circuit consisting of the excitation coil 134 and armature 133 and the secondary side circuit consisting of the movable and fixed contacts 123 and 121 is small so that as a result, the withstand voltage is low.
In the electromagnetic relay shown in FIG. 8 (that of Japanese Patent No. 3011334), a guide wall 211 consisting of an insulating material is present between the excitation coil 234 and the movable and fixed contacts 221 and 222. However, only the operating part 235 fastened to the armature 233 is present between the armature 233 and the movable and fixed contact 221 and 222. As a result, the insulating distance between the armature 233 and the movable and fixed contacts 221 and 222 is extremely small.
Accordingly, it is an object of the present invention is to provide an electromagnetic relay which avoids the above-mentioned problems and makes it possible to increase the insulating distance between the primary side circuit consisting of the excitation coil and armature, and the secondary side circuit consisting of the movable and fixed contacts, so that the withstand voltage can be increased.
An electromagnetic relay in accordance with the present invention comprises a substantially C-shaped flat-plate-form yoke which has a body extending in a horizontal direction and first and second legs extending downward from both ends of the body, and an insulating winding frame which has a winding body attached to the body of the C-shaped flat-plate-form yoke, and which has an excitation coil wound around the circumference of the winding body. The electromagnetic relay also includes an armature having a horizontal portion which extends in the horizontal direction, and on which an insulating operating part is arranged, a pivoting shaft extending from one end of the horizontal portion in the direction of extension of the first leg, and a vertical portion which extends from the other end of the horizontal portion, and which contacts the second leg when the excitation coil is excited. An insulating base housing supports both of the first and second legs of the yoke, and has a recess or hole that receives a shaft portion formed on the lower end of the pivoting shaft of the armature. A movable contact and a fixed contact are attached to the base housing and contact each other as a result of the pressing of the operating part. The base housing has a first insulating wall extending between the excitation coil and the armature and has a second insulating wall that blocks the space between the movable and fixed contacts and the armature. The operating part presses the movable contact via a hole formed in substantially the central portion of the second insulating wall.
As used herein, the term xe2x80x9csubstantially C-shapedxe2x80x9d includes shapes having corners.